#: 5881 S1/General Interest
    05-Aug-90  16:40:57
Sb: #5804-Disk fragmentation
Fm: Mark Griffith 76070,41
To: DICK SHARP 75266,2621

Dick

Fragmentation is a real problem on many systems, I'm not denying that.  What I
meant is it mostly depends on how you use your OS9 system.  If you use copy and
file manipulation utilities that are fairly intelligent (i.e. those written by
some of the users here) these utilities pre-extend the file before writing to
it by finding the size of the file to be copied.  This cuts down dramatically
on fragmentation.  Also, if one of the better make directory utilities is used
that also pre-extends, then again fragmentation is reduced. In addition,
setting the sector allocation size in the device descriptor has lots to do with
it.

But, if you have a utility that appends to a file by simply opening it and then
writing, that file will become fragmented fairly quickly.  Given that the
number of sectors allow for in a file's descriptor sector is limited to 48, a
badly fragmented file could get to the point where you can't write to it any
more.  I'm not sure what error is returned at this point, probably error #217
(segment table full), but I have never seen one.

Files that do become fragmented are easily fixed by simply copying them to a
temp file and then deleting and renaming.   Now if we are talking about overall
disk fragmentation, where the files become spread all around a disk, then this
is a little different, but still not a problem.  OS9 is pretty good in the way
it finds space for a file, usually keeping everything pretty tight.

Mark